• Qaisar Hussain Siraj
  • Nigora Rasulova


Parathyroid hormone is responsible for calcium homeostasis. Hypocalcaemia activates the calcium-sensing receptor on the surface of the parathyroid cell to release parathyroid hormone, which directly acts on the skeleton mobilising calcium from the bone. It directly stimulates Ca2+ reabsorption from the distal convoluted tubules of the kidneys and acts on the kidneys increasing the conversion of 25-hydroxy vitamin D to its active form of 1,25-dihydroxy vitamin D, which increases calcium absorption by the proximal tubules and the gut, and promotes calcium reabsorption in the ascending limb of loop of Henle, distal tubule, and collecting tubule. These actions lead to increased plasma Ca2+ levels.


Calcium homeostasis Parathyroid hormone Dihydroxy vitamin D3 Hypocalcaemia Calcium homeostasis Calcitriol Hypocalcaemia Calcium-sensing receptors Hypercalcaemia Phosphate Calcitonin Renal reabsorption Osteoclasts Amino acids Loop of Henle Vitamin D 25-Hydroxy vitamin D Dihydroxycholecalciferol Hyperparathyroidism Intestinal absorption Bone resorption Albumins Muscle contraction 


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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Qaisar Hussain Siraj
    • 1
  • Nigora Rasulova
    • 1
  1. 1.Department of Nuclear MedicineFarwaniya HospitalKuwaitKuwait

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